This paper presents a description and analysis of the tonal system of Moro, a Kordofanian language of Sudan, showing that the distribution of H(igh) tone is sensitive to a number of morphological and prosodic factors. First, we demonstrate that the distribution of H on nouns is sensitive to the OCP, both within roots and with affixes. Nouns also exhibit lexical distinctions between forms that exhibit unbounded rightward spreading of H and those that show no spreading. We model this distinction using cophonologies. While the distribution of H on Moro verb stems bears someWe are immensely grateful to our Moro speakers, Elyasir Julima and Ikhlas Elahmer, for sharing their language with us. We thank audiences at the 45 th Annual Meeting of the Chicago Linguistic Society, the Annual Conference on African Linguistics 37 and 40, the Massachusetts Institute of Technology, the University of Florida, the University of California, Santa Barbara and Harvard University for useful feedback and comments. We appreciate in-depth comments and discussion from Eric Baković, Larry Hyman, Victor Manfredi, Andrew Nevins, David Odden, and participants in the San Diego Phonology Interest Group and UCSD Phonetics Laboratory meetings. The members of the Moro Language Project, particularly Farrell Ackerman and George Gibbard, helped in numerous, immeasurable ways in both checking the data and refining the analysis. Finally, two anonymous reviewers and the associate editors, Michael Kenstowicz and Junko Itô, provided us with challenging comments and advice for improving the paper, for which we are grateful. Portions of Sect. 4 of this paper will appear with a slightly different analysis under the title 'Syllable weight and high tone in Moro' in Proceedings from the Annual Meeting of the Chicago Linguistic Society 45. This material is based upon research supported by the National Science Foundation under Grant No. 0745973 'Moro Language Project'. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation (NSF). P. Jenks ( ) Department of Linguistics, Harvard University, 3rd Floor, Boylston Hall, Cambridge, MA 02138, USA e-mail: pjenks@fas.harvard.edu S. Rose Department of Linguistics, University of California, San Diego, 9500 Gilman Drive #108, La Jolla, CA 92093-0108, USA e-mail: rose@ling.ucsd.edu 212 P. Jenks, S. Rose similarities to nouns, crucial differences emerge. Rightward H tone spreading is binary on verbs, and sensitive to the weight of the syllable in terms of both the presence of an onset and a coda. We model this effect as H tone spreading within a binary foot. Furthermore, unlike nouns, underlying representations play little role in the distribution of H on verb roots. H tone is predictably distributed within a morphological category, the derived stem (D-stem), similar to a constituent recognized in Bantu languages (e.g. Downing 2000). Finally, we analyze competition between H associated with ...